Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 188
Filtrar
1.
Chemistry ; : e202401275, 2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38656605

RESUMO

With a focus on Mn based organometallic compounds with suitable physico-chemical properties to serve as precursors for chemical vapor deposition (CVD) and atomic layer deposition (ALD) of Mn-containing materials, systematic synthetic approaches with ligand variation, detailed characterization, and theoretical input from density functional theory (DFT) studies are presented. A series of new homoleptic all-nitrogen and mixed oxygen/nitrogen-coordinated Mn(II) complexes bearing the acetamidinate, formamidinate, guanidinate and ß-ketoiminate ligands have been successfully synthesized for the first time. The specific choice of these ligand classes with changes in structure and coordination sphere and side chain variations result in significant structural differences whereby mononuclear and dinuclear complexes are formed. This was supported by density functional theory (DFT) studies. The compounds were thoroughly characterized by single crystal X-ray diffraction, magnetic measurements, mass spectrometry and elemental analysis. To evaluate their suitability as precursors for deposition of Mn-based materials, the thermal properties were investigated in detail. Mn(II) complexes possessing the most promising thermal properties, namely Bis(N,N´-ditertbutylformamidinato)manganese(II) (IV) and Bis(4-(isopropylamino)pent-3-en-2-onato)manganese(II) (ßIII) were used in reactivity studies with DFT to explore their interaction with oxidizing co-reactants such as oxygen and water which will guide future CVD and ALD process development.

2.
Anat Sci Educ ; 2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38659288

RESUMO

Fidelity between teaching activities and assessment methods is an important goal of knowledge and performance evaluations in medical education. Ideally, assessment methods provide evidence of learning that reflects the types of knowledge described in the learning objectives of the course. The most reliable assessments involve the same or similar tasks as those used during the instructional components of the course. Our preclinical human anatomy course includes, in addition to traditional lecture and cadaver-based laboratory learning activities, a series of applied human anatomy learning activities intended to emphasize human anatomy as it is encountered in living human individuals. The learning activities involve psychomotor behaviors including inspection, palpation, and auscultation, techniques used in the physical examination, as well as other activities designed to emphasize anatomical structures and tissues as they may be found in patient populations. We describe here our method for measuring student success in learning human anatomy in this manner, highlighting the direct linkage between the learning activities and the assessment tasks. We describe our performance scoring method and how we include this data in the calculation of an anatomy examination grade. As an indicator of our success with this approach, we include performance scores for the applied anatomy questions included on the laboratory component of our unit examinations for two successive academic years. We conclude with summary comments from students regarding the applied anatomy learning activities and assessment approach and offer suggestions for addressing specific challenges associated with the use of these types of assessment methods.

3.
Dalton Trans ; 53(18): 7711-7720, 2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38619887

RESUMO

Thin films of Al as interconnect materials and those of AlN as wide bandgap semiconductor and piezoelectric material are of great interest for microelectronic applications. For the fabrication of these thin films via chemical vapor deposition (CVD) based routes, the available precursor library is rather limited, mostly comprising aluminium alkyls, chlorides, and few small amine-stabilized aluminium hydrides. Herein, we focused on rational precursor development for Al, their characterization and comparison to existing precursors comprising stabilized aluminium hydrides. We present and compare a series of potentially new and reported aluminium hydride precursors divided into three main groups with respect to their stabilization motive, and their systematic structural variation to evaluate the physicochemical properties. All compounds were comprehensively characterized by means of nuclear magnetic resonance spectroscopy (NMR), Fourier-transform infrared spectroscopy (FTIR), elemental analysis (EA), electron-impact ionization mass spectrometry (EI-MS) and thermogravimetric analysis (TGA). Promising representatives were further evaluated as potential single source precursors for aluminium metal formation in proof-of-concept experiments. Structure and reaction enthalpies with NH3 or H2 as co-reactants were calculated via first principles density functional theory simulations and show the great potential as atomic layer deposition (ALD) precursors for Al and AlN thin films.

4.
Nanotechnology ; 35(28)2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38522104

RESUMO

Surface enhanced Raman spectroscopy (SERS) is a powerful analytical technique that has found application in the trace detection of a wide range of contaminants. In this paper, we report on the fabrication of 2D silver nanodendrites, on silicon chips, synthesized by electrochemical reduction of AgNO3at microelectrodes. The formation of nanodendrites is tentatively explained in terms of electromigration and diffusion of silver ions. Electrochemical characterization suggests that the nanodendrites do not stay electrically connected to the microelectrode. The substrates show SERS activity with an enhancement factor on the order of 106. Density functional theory simulations were carried out to investigate the suitability of the fabricated substrate for pesticide monitoring. These substrates can be functionalized with cyclodextrin macro molecules to help with the detection of molecules with low affinity with silver surfaces. A proof of concept is demonstrated with the detection of the herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA).

5.
Clin Exp Dent Res ; 10(1): e833, 2024 02.
Artigo em Inglês | MEDLINE | ID: mdl-38345521

RESUMO

OBJECTIVES: In this study, the aim was to investigate the medium- to long-term impact of peri-implantitis treatment upon clinical parameters and implant stability quotient values and to ascertain if magnetic resonance frequency analysis can be used as a diagnostic tool to demonstrate postoperative healing following treatment of peri-implantitis. MATERIALS AND METHODS: A total of n = 26 patients (n = 86 implants) diagnosed with peri-implantitis were recruited for this prospective cohort study and four different treatment modalities were used. Baseline measurements of a number of clinical parameters as well as implant stability measurements in the form of ISQ were recorded. These measurements were repeated at 6, 12, and 24-36 months following treatment. Analysis of variance was performed for all implants treated as well as separately for each treatment modality. A regression model was also used to determine factors affecting ISQ measurements over time. RESULTS: Treatment of peri-implantitis resulted in significant improvements of both average PPDs and BOP (p < .0001 and p < .01). ISQ values marginally improved initially for all treatment modalities, but improvement was only maintained for 2-3 years in treatment modalities I (+1.28), III (+1.49), and IV (+2.92). There was a statistically significant negative linear correlation between average PPD and the ISQ values recorded both at baseline (r = -.618, p < 0.0001) and at 2/3 years (r = -.604, p < 0.0001). CONCLUSION: Over the 2-3-year follow-up period, all four treatment modalities led to improved clinical and radiographic peri-implant parameters but implant stability posttreatment, as indicated by the fact that the recorded ISQ scores remained stable. As a result, use of MRFA as an adjunct to the traditionally used periodontal and radiographic tools for the evaluation of postoperative implant stability following the treatment of peri-implant disease cannot be recommended.


Assuntos
Implantes Dentários , Peri-Implantite , Humanos , Peri-Implantite/diagnóstico , Peri-Implantite/cirurgia , Implantes Dentários/efeitos adversos , Seguimentos , Estudos Prospectivos
6.
Vet Clin North Am Small Anim Pract ; 54(3): 559-575, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38160099

RESUMO

Stereotactic radiotherapy (SRT) involves the precise delivery of highly conformal, dose-intense radiation to well-demarcated tumors. Special equipment and expertise are needed, and a unique biological mechanism distinguishes SRT from other forms of external beam radiotherapy. Families find the convenient schedules and minimal acute toxicity of SRT appealing. Common indications in veterinary oncology include nasal, brain, and bone tumors. Many other solid tumors can also be treated, including spinal, oral, lung, heart-base, liver, adrenal, and prostatic malignancies. Accessibility of SRT is improving, and new data are constantly emerging to define parameters for appropriate case selection, radiation dose prescription, and long-term follow-up.


Assuntos
Neoplasias Encefálicas , Neoplasias , Radioterapia (Especialidade) , Radiocirurgia , Animais , Radiocirurgia/veterinária , Neoplasias/radioterapia , Neoplasias/veterinária , Neoplasias Encefálicas/veterinária
7.
Methods Mol Biol ; 2696: 199-210, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37578724

RESUMO

The Nod-like Receptor (NLR) apoptosis inhibitory proteins (NAIPs) are cytosolic receptors that sense cytosolic bacterial proteins. NAIP ligation induces its association with NLRC4, leading to the assembly of the NAIP/NLRC4 inflammasome, which induces the activation of the caspase-1 protease. Caspase-1 then cleaves pro-interleukin (IL)-1ß, pro-IL-18, and gasdermin D and induces a form of pro-inflammatory cell death, pyroptosis. These processes culminate in host defense against bacterial infection. Here we describe methods for activating NAIP/NLRC4 inflammasome signalling in human and murine macrophages and quantifying inflammasome-induced cell death.


Assuntos
Proteínas de Ligação ao Cálcio , Inflamassomos , Animais , Camundongos , Humanos , Inflamassomos/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas Reguladoras de Apoptose/metabolismo , Morte Celular , Caspases/metabolismo , Caspase 1/metabolismo , Proteínas Adaptadoras de Sinalização CARD/metabolismo
8.
ACS Appl Mater Interfaces ; 15(36): 42737-42745, 2023 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-37650582

RESUMO

Hexagonal boron nitride (h-BN) is a well-known layered van der Waals (vdW) material that exhibits no spontaneous electric polarization due to its centrosymmetric structure. Extensive density functional theory (DFT) calculations are used to demonstrate that doping through the substitution of B by isovalent Al and Ga breaks the inversion symmetry and induces local dipole moments along the c-axis, which promotes a ferroelectric (FE) alignment over antiferroelectric. For doping concentrations below 25%, a "protruded layered" structure in which the dopant atoms protrude out of the planar h-BN layers is energetically more stable than the flat layered structure of pristine h-BN or a wurtzite structure similar to w-AlN. The computed polarization, between 7.227 and 21.117 µC/cm2, depending on dopant concentration and the switching barrier (16.684 and 45.838 meV/atom) for the FE polarization reversal are comparable to that of other well-known FEs. Interestingly, doping of h-BN also induces a large negative piezoelectric response in otherwise nonpiezoelectric h-BN. For example, we compute d33 of -24.214 pC/N for Ga0.125B0.875N, which is about 5 times larger than that of pure w-AlN (5 pC/N), although the computed e33 (-1.164 C/m2) is about 1.6 times lower than that of pure w-AlN (1.462 C/m2). Because of the layered structure, the rather small elastic constant C33 provides the origin of the large d33. Moreover, doping makes h-BN an electric auxetic piezoelectric. We also show that ferroelectricity in doped h-BN may persist down to its trilayer, which indicates high potential for applications in FE nonvolatile memories.

9.
J Phys Chem C Nanomater Interfaces ; 127(28): 13651-13658, 2023 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-37492191

RESUMO

Early transition metals ruthenium (Ru) and cobalt (Co) are of high interest as replacements for Cu in next-generation interconnects. Plasma-enhanced atomic layer deposition (PE-ALD) is used to deposit metal thin films in high-aspect-ratio structures of vias and trenches in nanoelectronic devices. At the initial stage of deposition, the surface reactions between the precursors and the starting substrate are vital to understand the nucleation of the film and optimize the deposition process by minimizing the so-called nucleation delay in which film growth is only observed after tens to hundreds of ALD cycles. The reported nucleation delay of Ru ranges from 10 ALD cycles to 500 ALD cycles, and the growth-per-cycle (GPC) varies from report to report. No systematic studies on nucleation delay of Co PE-ALD are found in the literature. In this study, we use first principles density functional theory (DFT) simulations to investigate the reactions between precursors RuCp2 and CoCp2 with Si substrates that have different surface terminations to reveal the atomic-scale reaction mechanism at the initial stages of metal nucleation. The substrates include (1) H:Si(100), (2) NHx-terminated Si(100), and (3) H:SiNx/Si(100). The ligand exchange reaction via H transfer to form CpH on H:Si(100), NHx-terminated Si(100), and H:SiNx/Si(100) surfaces is simulated and shows that pretreatment with N2/H2 plasma to yield an NHx-terminated Si surface from H:Si(100) can promote the ligand exchange reaction to eliminate the Cp ligand for CoCp2. Our DFT results show that the surface reactivity of CoCp2 is highly dependent on substrate surface terminations, which explains why the reported nucleation delay and GPC vary from report to report. This difference in reactivity at different surface terminations may be useful for selective deposition. For Ru deposition, RuCp2 is not a useful precursor, showing highly endothermic ligand elimination reactions on all studied terminations.

10.
J Chem Phys ; 159(3)2023 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-37458350

RESUMO

Metal oxide semiconductors constitute a vast group of materials whose physical properties are greatly affected by native defects. For decades, x-ray photoelectron spectroscopy (XPS) has been widely used in defect analysis. However, correct interpretation of XPS results remains a difficult task. In this work, we present a detailed first-principles study on the core-level shift of the most stable and commonly cited crystal imperfections in ZnO, including O and -OH species at the surface with different coverages and bulk defects, including O interstitial (Oi), O vacancy in the +2 charge state (Vo2+), and the neutral vacancy (Vo0). The O1s core level spectrum is simulated and compared with experiments to understand the correlation between local atomic structures and features in the O1s spectrum. In particular, our results indicate that the widely adopted assignment in the defect analysis of ZnO, which links the defect peak in XPS to Vo, the most stable defect, is very likely a misinterpretation. Theoretical analysis indicates that there are no distinguishable XPS features arising from the Vo defect. Furthermore, we show that the commonly observed defect-related peak instead arises due to Oi or specific surface configurations. Given the importance of native defects in materials performance, misinterpretation of XPS results may lead to erroneous conclusions regarding materials properties. This work provides a first-principles basis for the analysis of oxide defects through XPS.

11.
Front Oncol ; 13: 1029108, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37274254

RESUMO

Introduction: Patients developing acute radiotherapy induced dermatitis or oral mucositis commonly experience pain. When severe, this radiotherapy-associated pain (RAP) can necessitate treatment breaks; unfortunately, in a variety of cancers, prolongation of the radiotherapy course has been associated with early cancer relapse and/or death. This is often attributed to accelerated repopulation, but it is unknown whether pain or pain signaling constituents might alter tumor behavior and hasten metastatic disease progression. We studied this by testing the hypothesis that severe acute RAP at one site can hasten tumor growth at a distant site. Methods: Mice underwent single fraction tongue irradiation (27 Gy, or 0 Gy "sham" control) to induce severe glossitis. At the time of maximal oral RAP, one of three luciferase-transfected tumor cell lines were injected via tail vein (4T1, B16F10, MOC2; each paired to their syngeneic host: BALB/c or C57BL/6); tumor burden was assessed via in vivo transthoracic bioluminescence imaging and ex vivo pulmonary nodule quantification. Survival was compared using Kaplan-Meier statistics. Results: Tongue irradiation and resultant RAP promoted lung tumor growth of 4T1-Luc2 cells in BALB/c mice. This effect was not a result of off-target radiation, nor an artefact of environmental stress caused by standard (subthermoneutral) housing temperatures. RAP did not affect the growth of B16F10-Luc2 cells, however, C57BL/6 mice undergoing tail vein injection of MOC2-Luc2 cells at the time of maximal RAP experienced early lung tumor-attributable death. Lung tumor growth was normalized when RAP was reduced by treatment with resiniferatoxin (300 µg/kg, subcutaneously, once). Discussion: This research points towards radiation-induced activation of capsaicin-responsive (TRPV1) neurons as the cause for accelerated growth of tumors at distant (unirradiated) sites.

12.
J Econ (Vienna) ; 139(3): 177-190, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37324503

RESUMO

To counteract excessive effort due to relative income comparison among identical agents, the literature suggests a tax response equal to the negative externality. Assuming a general income distribution, we show that an optimal tax must be higher under a general social welfare function, to not only reduce inefficiency but also inequality. We recommend a practical tax response to stronger comparison - to hold employment constant, which does not require unrealistic information including unobservable comparison. Surprisingly, the tax response will dominate the comparison effect and reduce labour supply or reverse "keeping up with the Joneses" on intensive margins, and also reverse the otherwise rising inequality. Supplementary Information: The online version contains supplementary material available at 10.1007/s00712-023-00821-2.

13.
Clin Anat ; 36(7): 986-992, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37212241

RESUMO

Student success in basic medical science courses is typically determined by their individual performance on examinations of various types. Previous research both within and outside medical education has shown that the use of educational assessment activities can increase learning as demonstrated by performance on subsequent examinations, a phenomenon known as the testing effect. Activities primarily designed and used for assessment and evaluation purposes can also be used as teaching opportunities. We developed a method for measuring and evaluating student accomplishment in a preclinical basic science course that incorporates both individual and collaborative efforts, encourages and rewards active participation, does not compromise the reliability of the assessment outcome and is perceived by the students as helpful and valuable. The approach involved a two-part assessment activity composed of an individual examination and a small group examination with each component differentially weighted in determining an overall examination score. We found that the method was successful in encouraging collaborative efforts during the group component and provided valid measures of student grasp of the subject matter. We describe the development and implementation of the method, provide data derived from its use in a preclinical basic science course and discuss factors to be addressed when utilizing this approach to ensure fairness and reliability of the outcome. We include brief summary comments from students regarding their impressions of the value of this method.


Assuntos
Educação Médica , Avaliação Educacional , Humanos , Reprodutibilidade dos Testes , Avaliação Educacional/métodos , Aprendizagem , Currículo
14.
J Vet Intern Med ; 37(3): 1119-1128, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37084035

RESUMO

BACKGROUND: Pituitary apoplexy refers to hemorrhage or infarction within the pituitary gland resulting in acute neurological abnormalities. This condition is poorly described in dogs. OBJECTIVES: To document presenting complaints, examination findings, endocrinopathies, magnetic resonance imaging (MRI), treatments, and outcomes of dogs with pituitary apoplexy. ANIMALS: Twenty-six client-owned dogs with acute onset of neurological dysfunction. METHODS: Retrospective case series. Dogs were diagnosed with pituitary apoplexy if MRI or histopathology documented an intrasellar or suprasellar mass with evidence of hemorrhage or infarction in conjunction with acute neurological dysfunction. Clinical information was obtained from medical records and imaging reports. RESULTS: Common presenting complaints included altered mentation (16/26, 62%) and gastrointestinal dysfunction (14/26, 54%). Gait or posture changes (22/26, 85%), mentation changes (18/26, 69%), cranial neuropathies (17/26, 65%), cervical or head hyperpathia (12/26, 46%), and hyperthermia (8/26, 31%) were the most frequent exam findings. Ten dogs (38%) lacked evidence of an endocrinopathy before presentation. Common MRI findings included T1-weighted hypo- to isointensity of the hemorrhagic lesion (21/25, 84%), peripheral enhancement of the pituitary mass lesion (15/25, 60%), brain herniation (14/25, 56%), and obstructive hydrocephalus (13/25, 52%). Fifteen dogs (58%) survived to hospital discharge. Seven of these dogs received medical management alone (median survival 143 days; range, 7-641 days) and 8 received medications and radiation therapy (median survival 973 days; range, 41-1719 days). CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with pituitary apoplexy present with a variety of acute signs of neurological disease and inconsistent endocrine dysfunction. Dogs that survive to discharge can have a favorable outcome.


Assuntos
Doenças do Cão , Hidrocefalia , Apoplexia Hipofisária , Neoplasias Hipofisárias , Cães , Animais , Apoplexia Hipofisária/terapia , Apoplexia Hipofisária/veterinária , Apoplexia Hipofisária/diagnóstico , Neoplasias Hipofisárias/complicações , Neoplasias Hipofisárias/diagnóstico por imagem , Neoplasias Hipofisárias/terapia , Neoplasias Hipofisárias/veterinária , Estudos Retrospectivos , Hidrocefalia/veterinária , Infarto/veterinária , Imageamento por Ressonância Magnética/veterinária , Doenças do Cão/diagnóstico por imagem , Doenças do Cão/terapia
15.
Clin Anat ; 36(8): 1081-1088, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36708162

RESUMO

The horseshoe kidney (HSK) is the most common congenital abnormality of the upper urinary tract with an incidence of approximately 1 in 500 in the general population. Although individuals with HSK are often asymptomatic, they are at increased risk for neoplasms, infections, ureteropelvic obstruction secondary to lithiasis or vascular compression. Direct injury from trauma is increased in these individuals as is the risk of intraoperative complications secondary to damage involving the typically complex renal or adrenal vascular supply. We briefly review etiological factors including renal and urinary system embryology, genetic mutations, abnormalities related to faulty cell signaling, aberrant cell migration, and other possible causes including environmental exposures and trauma. In addition, we call attention to factors that might influence the success of surgical procedures in patients with HSK. We argue that an understanding of possible etiologies of the HSK and its different subtypes may be useful when planning surgical procedures or considering risk-benefit ratios associated with different surgical options. We briefly present the organization of a HSK in a 100-year-old male demonstrating an unusual vascular supply discovered during a dissection laboratory session in a medical school anatomy course. We describe the structure of the HSK, the position and relationships of the HSK to other structures within the abdomen, and the associated vascular relationships.


Assuntos
Cavidade Abdominal , Rim Fundido , Masculino , Humanos , Idoso de 80 Anos ou mais , Rim Fundido/genética , Rim/irrigação sanguínea
16.
Clin Anat ; 36(1): 83-91, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36216782

RESUMO

The COVID-19 (COVID) pandemic forced changes in how medical curricula are organized and delivered. In addition to disease mitigation strategies, other curricular modifications were required to maintain educational effectiveness and student and faculty safety. While these changes appear to be successful in their primary goal, their effect on learning and other important educational outcomes is less well understood. We describe changes to our anatomy course and describe their effects on summative examination scores. We compared anatomy examination scores from 4 years prior to COVID with scores from the 2 years following COVID mandated changes in an effort to determine the effectiveness of our course modifications. Examination scores for the first of four successive Blocks of instruction following the implementation of curricular changes demonstrated a lower mean score and greater range of scores than for the four pre-COVID years. Pre-COVID and post-COVID scores for Blocks II, III, and IV were comparable. Our results indicate that our changes to the anatomy curriculum did not prevent a performance decline during the first Block of instruction only. However, students were able to successfully adapt to these changes during the remainder of the course. We discuss factors that may have accounted for the Block I performance decline and call attention to changes within the larger curriculum that may have affected student performance.


Assuntos
Anatomia , COVID-19 , Educação de Graduação em Medicina , Estudantes de Medicina , Humanos , Avaliação Educacional/métodos , Currículo , Aprendizagem , Anatomia/educação , Educação de Graduação em Medicina/métodos
17.
Beilstein J Nanotechnol ; 13: 1240-1255, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36415852

RESUMO

The development of hybrid inorganic-organic films with well-controlled properties is important for many applications. Molecular layer deposition (MLD) allows the deposition of these hybrid films using sequential, self-limiting reactions, similar to atomic layer deposition (ALD). In this paper, we use first principles density functional theory (DFT) to investigate the growth mechanism of titanium-containing hybrid organic-inorganic MLD films, known as "titanicones". We investigate in detail the chemistry between the most common Ti precursors, namely titanium tetrachloride (TiCl4) and tetrakis(dimethylamido)titanium (Ti(DMA)4), and ethylene glycol (EG) and glycerol (GL) as the organic precursors. We analyse the impact of the substrate on the initial MLD reactions in titanicone film growth using three different surface models: anatase TiO2, rutile TiO2 and Al2O3. Calculated energetics show that while TiCl4 is reactive towards the anatase and rutile TiO2 surfaces, it is not reactive towards the Al2O3 surface. Ti(DMA)4 is reactive towards all surfaces. This is attributed to the stronger Ti-Cl bonds in TiCl4 compared to Ti-N bonds in Ti(DMA)4. Ti(DMA)4 also shows high reactivity to the organics compared to TiCl4. Double reactions of EG and GL with the TiCl3 species from TiCl4 and TiDMA species from Ti(DMA)4 are also explored to better understand the origin of the different thicknesses of EG-titanicone and GL-titanicone films observed in experimental work. We find that EG and GL coupled with TiCl4 can orient in a flat lying configuration on anatase while on rutile, the preferred orientation is upright. When combined with Ti(DMA)4, EG and GL prefer the flat lying configuration on all surfaces. This work shows that the choice of the surface and the metallic precursor has a major impact on the behaviour of organic species. DFT findings provide motivation to develop a low temperature rutile TiO2/titanicone film suggesting that the desired film growth could be achieved.

18.
Catal Sci Technol ; 12(14): 4511-4523, 2022 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-35924073

RESUMO

The promotional effects on photocatalytic hydrogen production of Cu x O clusters deposited using atomic layer deposition (ALD) on P25 TiO2 are presented. The structural and surface chemistry study of Cu x O/TiO2 samples, along with first principles density functional theory simulations, reveal the strong interaction of ALD deposited Cu x O with TiO2, leading to the stabilization of Cu x O clusters on the surface; it also demonstrated substantial reduction of Ti4+ to Ti3+ on the surface of Cu x O/TiO2 samples after Cu x O ALD. The Cu x O/TiO2 photocatalysts showed remarkable improvement in hydrogen productivity, with 11 times greater hydrogen production for the optimum sample compared to unmodified P25. With the combination of the hydrogen production data and characterization of Cu x O/TiO2 photocatalysts, we inferred that ALD deposited Cu x O clusters have a dual promotional effect: increased charge carrier separation and improved light absorption, consistent with known copper promoted TiO2 photocatalysts and generation of a substantial amount of surface Ti3+ which results in self-doping of TiO2 and improves its photo-activity for hydrogen production. The obtained data were also employed to modify the previously proposed expanding photocatalytic area and overlap model to describe the effect of cocatalyst size and weight loading on photocatalyst activity. Comparing the trend of surface Ti3+ content increase and the photocatalytically promoted area, calculated with our model, suggests that the depletion zone formed around the heterojunction of Cu x O-TiO2 is the main active area for hydrogen production, and the hydrogen productivity of the photocatalyst depends on the surface coverage by this active area. However, the overlap of these areas suppresses the activity of the photocatalyst.

19.
Nanoscale ; 14(32): 11676-11683, 2022 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-35912821

RESUMO

Flexible two-dimensional (2D) piezoelectric materials are promising for applications in wearable electromechanical nano-devices such as sensors, energy harvesters, and actuators. A large piezo-response is required for any practical applications. Based on first-principles calculations, we report that ferroelectric TiOX2 and multiferroelectric VOX2 (X = F, Cl, and Br) monolayers exhibit large in-plane stress (e11) and strain (d11) piezoelectric coefficients. For example, the in-plane piezo-response of TiOBr2 (both e11 = 28.793 × 10-10 C m-1 and d11 = 37.758 pm V-1) is about an order of magnitude larger than that of the widely studied 1H-MoS2 monolayer, and also quite comparable to the giant piezoelectricity of group-IV monochalcogenide monolayers, e.g., SnS. Moreover, the d11 of MOX2 monolayers - ranging from 29.028 pm V-1 to 37.758 pm V-1 - are significantly higher than the d11 or d33 of commonly used 3D piezoelectrics such as w-AlN (d33 = 5.1 pm V-1) and α-quartz (d11 = 2.3 pm V-1). Such a large d11 of MOX2 monolayers originates from low in-plane elastic constants with large e11 due to large Born effective charges (Zij) and atomic sensitivity to an applied strain. Moreover, we show the possibility of opening a new way of controlling piezoelectricity by applying a magnetic field.

20.
J Am Vet Med Assoc ; 260(12): 1496-1506, 2022 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-35905155

RESUMO

OBJECTIVE: To describe oncologic outcomes following administration of a uniform stereotactic radiotherapy protocol (SRT; 10 Gy X 3) for canine intranasal tumors and to identify whether any clinical or dosimetric factors were predictive of event-free or overall survival time (EFST or OST). ANIMALS: 129 dogs. PROCEDURES: In this single-institution retrospective study, the medical records database was searched for canine nonlymphomatous intranasal tumors treated with 10 Gy X 3 SRT between August 2013 and November 2020. Findings regarding adverse effects and outcomes were analyzed overall, for dogs grouped on the basis of life stage (mature adult, senior, or end of life), and for treatment-related or tumor-related variables to identify potential predictors of outcome. RESULTS: After SRT, most dogs clinically improved with minimal acute radiotoxicity. The median EFST was 237 days; median OST was 542 days. Receipt of other tumor-directed therapies before or after SRT was associated with improved EFST in senior dogs (hazard ratio [HR], 0.416) and improved OST in mature adult (HR, 0.241) and senior dogs (HR, 0.348). In senior dogs, administration of higher near-minimum radiation doses was associated with improved EFST (HR, 0.686) and OST (HR, 0.743). In senior dogs, chondrosarcoma was associated with shorter OST (HR, 7.232), and in dogs at end of life, having a squamous cell or transitional carcinoma was associated with worse EFST (HR, 6.462). CLINICAL RELEVANCE: This SRT protocol results in improved quality of life and prolonged OST for dogs of all life stages. Radiation protocol optimization or use of multimodal therapy may further improve outcomes.


Assuntos
Neoplasias Ósseas , Condrossarcoma , Doenças do Cão , Radiocirurgia , Cães , Animais , Estudos Retrospectivos , Doenças do Cão/cirurgia , Qualidade de Vida , Radiocirurgia/métodos , Radiocirurgia/veterinária , Condrossarcoma/veterinária , Neoplasias Ósseas/veterinária , Morte , Resultado do Tratamento
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...